1. Technical Field
The present invention relates to a liquid ejecting head and a liquid ejecting apparatus.
2. Related Art
For example, in liquid ejecting apparatuses such as ink jet printers, a liquid ejecting head having a piezoelectric element for ejecting liquid such as ink is known. The liquid ejecting head of this type is configured to be capable of changing the pressure in a pressure generating chamber formed below a diaphragm by the piezoelectric element which deforms the diaphragm using drive signals or the like. Accordingly, liquid such as ink supplied from nozzle orifices into the pressure generating chamber are ejected. Among the liquid ejecting heads as described above, there is a type having a structure in which a piezoelectric layer is covered with an upper electrode for the purpose of protecting the piezoelectric layer of the piezoelectric element which is vulnerable to destruction due to external factors such as moisture or the like (for example, see JP-A-2009-172878, FIG. 2).
However, when the piezoelectric element as disclosed in JP-A-2009-172878 is driven, the piezoelectric layer of the piezoelectric element is subjected to deformation as a piezoelectric body on the inside of a boundary of a positive area defined by an area in which the upper electrode and a lower electrode are overlapped with each other with the intermediary of the piezoelectric layer therebetween because an electric field is applied thereto. In contrast, the piezoelectric layer of the piezoelectric element is not subjected to deformation as a piezoelectric body on the outside thereof because an electric field is not applied thereto. Therefore, there arises a problem such that a local strain is concentrated on a portion near the boundary of the positive area, and hence high probability of generation of cracks in the piezoelectric layer may be resulted.